In medical applications, apparatuses are often used which are heavy or which have to be guided extremely precisely. It is therefore necessary to provide mountings for such apparatuses. U.S. Pat. No. 5,657,429 and U.S. Pat. No. 5,553,198, for example, each disclose a robot system in which a robot arm can be fastened by means of an adaptor on a cart or to an operating table. The robot arm is fixedly connected to the adaptor and connected via a mechanism either to the operating table or to the cart.